mitmproxy: Update net/mitmproxy to 4.0.1

pkgsrc changes:
- Take MAINTAINERship
- Sync DEPENDS with setup.py
- Add Python 3.5 to PYTHON_VERSIONS_INCOMPATIBLE (mitmproxy now requires Python
  3.6)

Changes:
mitmproxy 4.0.1
---------------
The previous release had a packaging issue, so we bumped it to
v4.0.1 and re-released it. This contains no actual bugfixes or
new features.

mitmproxy 4.0
-------------
Features
--------
* mitmproxy now requires Python 3.6!
* Moved the core to asyncio - which gives us a very significant performance
  boost!
* Reduce memory consumption by using `SO_KEEPALIVE` (#3076)
* Export request as httpie command (#3031)
* Configure mitmproxy console keybindings with the keys.yaml file. See docs
  for more.

Breaking Changes
----------------
* The --conf command-line flag is now --confdir, and specifies the mitmproxy
  configuration directory, instead of the options yaml file (which is at
  `config.yaml` under the configuration directory).
* `allow_remote` got replaced by `block_global` and `block_private` (#3100)
* No more custom events (#3093)
* The `cadir` option has been renamed to `confdir`
* We no longer magically capture print statements in addons and translate
  them to logs. Please use `ctx.log.info` explicitly.

Bugfixes
--------
* Correctly block connections from remote clients with IPv4-mapped IPv6
  client addresses (#3099)
* Expand `~` in paths during the `cut` command (#3078)
* Remove socket listen backlog constraint
* Improve handling of user script exceptions (#3050, #2837)
* Ignore signal errors on windows
* Fix traceback for commands with un-terminated escape characters (#2810)
* Fix request replay when proxy is bound to local interface (#2647)
* Fix traceback when running scripts on a flow twice (#2838)
* Fix traceback when killing intercepted flow (#2879)
* And lots of typos, docs improvements, revamped examples, and general fixes!

(leot)